Next.js (App Router) quickstart
1. Install hypertune
hypertune
Once you have a Next.js application (using the App Router) ready, install the hypertune
and server-only
packages:
npm install hypertune server-only
2. Set environment variables
Set the following environment variables in your .env
file:
NEXT_PUBLIC_HYPERTUNE_TOKEN=token
HYPERTUNE_FRAMEWORK=nextApp
HYPERTUNE_OUTPUT_DIRECTORY_PATH=generated
Replace token
with your main project token which you can find in the Settings tab of your project.
3. Generate the client
Generate a type-safe client to access your flags by running:
npx hypertune
4. Use the client
Add a new file called getHypertune.ts
that exports a getHypertune
function:
import 'server-only'
import { unstable_noStore as noStore } from 'next/cache'
import { createSource } from '@/generated/hypertune'
const hypertuneSource = createSource({
token: process.env.NEXT_PUBLIC_HYPERTUNE_TOKEN!,
})
export default async function getHypertune({
isRouteHandler = false,
}: {
isRouteHandler?: boolean
} = {}) {
noStore()
await hypertuneSource.initIfNeeded()
hypertuneSource.setRemoteLoggingMode(
isRouteHandler ? 'normal' : 'off'
)
return hypertuneSource.root({
args: {
context: {
environment: process.env.NODE_ENV,
user: {
id: 'e23cc9a8-0287-40aa-8500-6802df91e56a',
name: 'Example User',
email: '[email protected]',
},
},
},
})
}
To use flags in Client Components, first wrap your app with the generated <HypertuneProvider>
component in your root layout:
import { HypertuneProvider } from '@/generated/hypertune.react'
import getHypertune from '@/lib/getHypertune'
import './globals.css'
export default async function RootLayout({
children,
}: Readonly<{
children: React.ReactNode
}>) {
const hypertune = await getHypertune()
const dehydratedState = hypertune.dehydrate()
const rootArgs = hypertune.getRootArgs()
return (
<HypertuneProvider
createSourceOptions={{
token: process.env.NEXT_PUBLIC_HYPERTUNE_TOKEN!,
}}
dehydratedState={dehydratedState}
rootArgs={rootArgs}
>
<html lang="en">
<body>{children}</body>
</html>
</HypertuneProvider>
)
}
Then use the generated useHypertune
hook:
'use client'
import { useHypertune } from '@/generated/hypertune.react'
export default function ClientComponent() {
const hypertune = useHypertune()
const exampleFlag = hypertune.exampleFlag({ fallback: false })
return <div>Example Flag: {String(exampleFlag)}</div>
}
Notes
Dynamic rendering: Calling
getHypertune
in your root layout makes your entire app dynamic. To keep parts of your app static (e.g. marketing pages), see (Static) Client Components.Hydration: Passing
dehydratedState
from the server instantly hydrates the SDK in the browser. This ensures you can use flags on the first render with no layout shift, flicker, or delay. If omitted, the SDK will initialize in the background and trigger a re-render once ready.Root args: Passing
rootArgs
from the server lets you reuse the root args fromgetHypertune
on the server. This is optional — you can also construct root args on the client.Content Security Policy: If you use a CSP, add the following to your
connect-src
directive:https://edge.hypertune.com https://gcp.fasthorse.workers.dev
. This enables reporting of flag evaluations, experiment exposures, and analytics events.
5. (Optional) Add the Hypertune Toolbar
The Hypertune Toolbar lets you view and override feature flags directly in your frontend. Follow the guide to add it to your app.
6. (Optional) Include a build-time snapshot
To improve reliability, you can include a snapshot of your flag logic in the generated client at build time. The SDK will instantly initialize from the snapshot first before fetching the latest flag logic from Hypertune Edge.
Add the following environment variable to your .env
file:
HYPERTUNE_INCLUDE_INIT_DATA=true
Then run npx hypertune
to regenerate the client.
You can keep the snapshot fresh by setting up a webhook to regenerate the client on every Hypertune commit. In this case, you don't need to initialize from Hypertune Edge at all, eliminating network latency and bandwidth, improving both performance and efficiency.
7. (Optional) Use Vercel Edge Config
If your Next.js app is deployed on Vercel, you can use Edge Config to initialize the Hypertune SDK on the server with near-zero latency.
1. Install the integration
Go to the Hypertune page in the Vercel Integrations marketplace and click "Add Integration".
Select your Vercel team and project.
Continue and log into Hypertune.
Connect your Hypertune project to a new or existing Edge Config store. Copy the displayed environment variables for later. They contain your Hypertune Token, Edge Config Connection String, and Edge Config Item Key.
Go to your Vercel dashboard and select the project you want to use the Hypertune integration with. Go to Settings > Environment Variables and add the following:
NEXT_PUBLIC_HYPERTUNE_TOKEN
, set to your Hypertune TokenEDGE_CONFIG
, set to your Edge Config Connection StringEDGE_CONFIG_HYPERTUNE_ITEM_KEY
, set to your Edge Config Item Key
2. Use the integration
Pull the environment variables to your .env.development.local
file by running:
vercel env pull .env.development.local
Install the @vercel/edge-config
package:
npm install @vercel/edge-config
Finally, update your getHypertune
function to create an Edge Config client and pass it along with your Edge Config Item Key when creating the Hypertune source:
import 'server-only'
import { createClient } from '@vercel/edge-config'
import { VercelEdgeConfigInitDataProvider } from 'hypertune'
import { unstable_noStore as noStore } from 'next/cache'
import { createSource } from '@/generated/hypertune'
const hypertuneSource = createSource({
token: process.env.NEXT_PUBLIC_HYPERTUNE_TOKEN!,
initDataProvider:
process.env.EDGE_CONFIG &&
process.env.EDGE_CONFIG_HYPERTUNE_ITEM_KEY
? new VercelEdgeConfigInitDataProvider({
edgeConfigClient: createClient(
process.env.EDGE_CONFIG
),
itemKey: process.env.EDGE_CONFIG_HYPERTUNE_ITEM_KEY,
})
: undefined,
})
export default async function getHypertune() {
noStore()
await hypertuneSource.initIfNeeded() // Check for flag updates
return hypertuneSource.root({
args: {
context: {
environment: process.env.NODE_ENV,
user: {
id: 'e23cc9a8-0287-40aa-8500-6802df91e56a',
name: 'Example User',
email: '[email protected]',
},
},
},
})
}
8. (Optional) Integrate with the Vercel Toolbar and Flags Explorer
1. Set up the Vercel Toolbar
Follow the guide to add the Vercel Toolbar to your local environment.
2. Generate a FLAGS_SECRET
environment variable
FLAGS_SECRET
environment variableOpen the Flags Explorer from the Toolbar and follow the prompts to generate a FLAGS_SECRET
environment variable and pull it locally with vercel env pull
.
3. Provide flag definitions to the Vercel Toolbar
Install the flags
package:
npm install flags
Then add a new route handler in app/.well-known/vercel/flags/route.ts
to provide flag definitions to the Vercel Toolbar using the generated vercelFlagDefinitions
constant:
import { createFlagsDiscoveryEndpoint } from 'flags/next'
import { vercelFlagDefinitions } from '../../../../generated/hypertune'
export const GET = createFlagsDiscoveryEndpoint(() => {
return { definitions: vercelFlagDefinitions }
})
4. Generate Vercel integration helpers
Add the following environment variable to your .env
file:
HYPERTUNE_PLATFORM=vercel
Then run npx hypertune
to regenerate the client.
5. Respect flag overrides set by the Vercel Toolbar
Update your getHypertune
function to respect flag overrides set by the Vercel Toolbar using the generated getVercelOverride
function:
import 'server-only'
import { unstable_noStore as noStore } from 'next/cache'
import { createSource } from '@/generated/hypertune'
import { getVercelOverride } from '@/generated/hypertune.vercel'
const hypertuneSource = createSource({
token: process.env.NEXT_PUBLIC_HYPERTUNE_TOKEN!,
})
export default async function getHypertune() {
noStore()
await hypertuneSource.initIfNeeded() // Check for flag updates
// Respect flag overrides set by the Vercel Toolbar
hypertuneSource.setOverride(await getVercelOverride())
return hypertuneSource.root({
args: {
context: {
environment: process.env.NODE_ENV,
user: {
id: 'e23cc9a8-0287-40aa-8500-6802df91e56a',
name: 'Example User',
email: '[email protected]',
},
},
},
})
}
6. Provide flag values to the Vercel Toolbar
Add the generated <VercelFlagValues>
component to your app to tell the Vercel Toolbar about your flag values:
import { HypertuneProvider } from '@/generated/hypertune.react'
import { VercelFlagValues } from '@/generated/hypertune.vercel'
import getHypertune from '@/lib/getHypertune'
import './globals.css'
export default async function RootLayout({
children,
}: Readonly<{
children: React.ReactNode
}>) {
const hypertune = await getHypertune()
const serverDehydratedState = hypertune.dehydrate()
const serverRootArgs = hypertune.getRootArgs()
return (
<HypertuneProvider
createSourceOptions={{
token: process.env.NEXT_PUBLIC_HYPERTUNE_TOKEN!,
}}
dehydratedState={serverDehydratedState}
rootArgs={serverRootArgs}
>
<html lang="en">
<body>
{children}
<VercelFlagValues flagValues={hypertune.get()} />
</body>
</html>
</HypertuneProvider>
)
}
9. (Optional) Integrate with Vercel's Flags SDK
You can integrate Hypertune with Vercel's Flags SDK to use Vercel's Flags pattern on the server, e.g. in Server Components, Route Handlers, or Middleware.
Install the required dependencies:
npm install flags @flags-sdk/hypertune @vercel/edge-config
Create a new file called flags.ts
that contains an identify
function and a hypertuneAdapter
, and defines your flag functions:
import { createHypertuneAdapter } from '@flags-sdk/hypertune'
import { Identify } from 'flags'
import { dedupe, flag } from 'flags/next'
import {
createSource,
flagFallbacks,
vercelFlagDefinitions as flagDefinitions,
Context,
RootFlagValues,
} from './generated/hypertune'
const identify: Identify<Context> = dedupe(
async ({ headers, cookies }) => {
return {
environment: process.env.NODE_ENV,
user: {
id: 'e23cc9a8-0287-40aa-8500-6802df91e56a',
name: 'Example User',
email: '[email protected]',
},
}
}
)
const hypertuneAdapter = createHypertuneAdapter<
RootFlagValues,
Context
>({
createSource,
flagFallbacks,
flagDefinitions,
identify,
})
export const exampleFlagFlag = flag(
hypertuneAdapter.declarations.exampleFlag
)
export const enableDesignV2Flag = flag(
hypertuneAdapter.declarations.enableDesignV2
)
To use flags, import and await your flag functions:
import { exampleFlagFlag } from '@/flags'
export default async function ServerComponent() {
const exampleFlag = await exampleFlagFlag()
return <div>Example Flag: {String(exampleFlag)}</div>
}
To use the Flags Explorer in the Vercel Toolbar, add a new route handler in app/.well-known/vercel/flags/route.ts
to provide flag definitions to it using the generated vercelFlagDefinitions
constant:
import { createFlagsDiscoveryEndpoint } from 'flags/next'
import { vercelFlagDefinitions } from '../../../../generated/hypertune'
export const GET = createFlagsDiscoveryEndpoint(() => {
return { definitions: vercelFlagDefinitions }
})
To use Vercel Edge Config with the Flags SDK, configure it via environment variables:
EXPERIMENTATION_CONFIG="https://edge-config.vercel.com/ecfg_xyz?token=abc"
EXPERIMENTATION_CONFIG_ITEM_KEY="hypertune_99999"
Or via the adapter:
import { createHypertuneAdapter } from '@flags-sdk/hypertune'
import { createClient } from '@vercel/edge-config'
import { Identify } from 'flags'
import { dedupe, flag } from 'flags/next'
import { VercelEdgeConfigInitDataProvider } from 'hypertune'
import {
createSource,
flagFallbacks,
vercelFlagDefinitions as flagDefinitions,
Context,
RootFlagValues,
} from './generated/hypertune'
const identify: Identify<Context> = dedupe(
async ({ headers, cookies }) => {
return {
environment: process.env.NODE_ENV,
user: {
id: 'e23cc9a8-0287-40aa-8500-6802df91e56a',
name: 'Example User',
email: '[email protected]',
},
}
}
)
const hypertuneAdapter = createHypertuneAdapter<
RootFlagValues,
Context
>({
createSource,
flagFallbacks,
flagDefinitions,
identify,
createSourceOptions: {
initDataProvider: new VercelEdgeConfigInitDataProvider({
edgeConfigClient: createClient(
'https://edge-config.vercel.com/ecfg_xyz?token=abc'
),
itemKey: 'hypertune_99999',
}),
},
})
export const exampleFlagFlag = flag(
hypertuneAdapter.declarations.exampleFlag
)
export const enableDesignV2Flag = flag(
hypertuneAdapter.declarations.enableDesignV2
)
Next steps
Now you can update the logic for exampleFlag
from the Hypertune UI without updating your code or waiting for a new build, deployment, or app release.
To add a new flag, create it in the Hypertune UI then regenerate the client.
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